In a communications device equipped with a plurality of antenna elements such as a diversity antenna, it is generally important to keep a sufficient electrical isolation between the antenna elements. A composite antenna of such kind is therefore provided with large spaces between antenna elements in order to ensure the electrical isolation between the adjoining elements.
Patent document 1, for instance, is one of the prior art documents known to be relevant to the invention of this patent application. Due to the increasing tendency in recent years toward downsizing of mobile communications terminals such as cellular phones, it has become difficult to keep sufficient spaces between adjoining antenna elements when such composite antennas are mounted, which often results in such circumstances that the electrical isolations are not properly maintainable.
Patent Document 1: Japanese Patent Unexamined Publication, No. 2003-298340